function f(a: number, b: number): number {
    return a + b
}

console.log(f(1, 2))

const obj = {name: "孙悟空", age: 18}
obj.name = "齐天大圣"

console.log(obj)
console.log(Promise)

let fn = (a: number, b: number) => a + b
fn(1,2)
fn(282,2131)